The invention relates to proximity detecting apparatus, and more particularly to infrared radiation proximity detectors.
Proximity detectors are devices utilized to detect the presence of objects moving within a prefixed area at a proximate distance from the detector. Such devices may use electrical waves, light waves, mechanical sensing apparatus, and the like, to sense the presence of the proximate objects.
However, the use of infrared radiation in the art of proximity detection presents problems unique of its own. Where the proximity detector is to be used out of doors, spurious radiation from the sun presents false signals which are detected by the detector. Cloud changes and bright sunlight reflections further exacerbate attempts to control the radiation impinging upon the detector. And where the proximity detector is to be used indoors, spurious radiation can also occur from incandescent lights.
Also, where the source of infrared radiation used by the detector is supplied by an infrared light-emitting diode, the inefficient radiation output capacilities found with ordinary light-emitting diodes impose power consumption and use limitation requirements in the design of such proximity detectors.